Method of inductive heating



Feb. 16, 1932. H. NEUHAUss 1,845,322

METHOD OF INDUCTIVE HEATING Filed ot. 24, 1928 Patented Feb. 16, 1932 PATENT orales mmmrcrr minces, or Dussmmonr, am. AssmNon. 'ro 'rnuax PHILADELPHIA, PENNSYLVANIA, yA RPORLTION F ,PENNSYL- nmrnon or mnuc'nva rra-arras Y Y aspnemmm catter a4, laas." sum n. mp4s.

My invention relates to the fusing YofL adherent coatings u on metal 'into union wlth the metal upon w 'ich they 'are coated.

' My purpose is to induce alternatingzcurrent llow throughja plate-or sheet for` the purpose of fusinga coating intounion with it.

y A further purpose is to provide for greater heating of the metal upon either side of the plate or sheet at will by mhcing the current o within that side largely or e'xclusivel or a ply the induction from boith sides o the plate concurrently or from the two sides successively as desired.

A. further purpose is to bend a plate or 5 sheet into'cyhndrical form so that it may be conveniently used as Ia'transform'er second- A further purpose is to provide` a form or support for a cylinder of bent initially-flat plate whereby the spacing of rtheinetal from an inductor primary may be determined and ma be made uniform.v e. f urther.. urposes will appear. in thespeciication and in the claims. y j t My invention relates both to the methods or rocesses involved and to apparatus by which they may be carried out. v t I have referred to illustrate m invention by views which are largely iagrammatic and which have been selected from the standpoint that they particularly well illustrate the principles involved. A. Y Figures 1 and 1a are sections intended to illustrate any sheet of metal carrying an adherent coating, covering or plating o f other vmetal upon one surface or carrying such coatings or coverings upon both` sides `or Figures 2 and 3 aredi'agrammatic views showing the same sheet of metal forming outer and inner'secondariesrespectively for electric inductor primaries.

Figures 4, 6 and 9 are longitudinal sections showing guides or supports for bent sheets to subject them 'to the best advantage to the induction' from inductor coils.

Figures 5 and 7 are sections of Figures 4 and 6 upon lines 5-5 and 7-7 respectively.

5 Figure 8 is an enlarged section corresponding generally to Figure 1 taken after fusion has en effected. .c t

In theA drawings similar numerals indicate like parts. A t My 'invention is intended to'apply tothe fusion of an adherent coating 14V or coatings 14, 14 upon the surface of asheet orstrip of metal 15', here viewed as a base, into union With the sheet. It applies tovthese coatings however they have been deposited upony or ap'- plied to the surface of the base metal. For example, the coatings may have been electroplated or applied by a metal gun,V or in any other manner by which adhesion of thel coatingto the base metal may be secured. I

acter have beenfused into 'contact withlthe base metal the form of'hollow inductor secondaries to which they had previously adhered but to the bestof my knowledge this rior to my invention'coatings of this charinvention has never been ap lied to initially 'I flat sheets'. The fusion of t ese coatin to sheets of initial plate metal, or of meta not in closed cylindrical'form I believe' to be new to me. v l

In Figures 2 and 3 I show the composite body 16, initially in sheet form, as bentinto form ofacylinder 16 surrounding a highfrequency inductor primary 17 in Figure 2 and surrounded by such an inductor 17 in Figure 3. In each caseI have shown 'a conventional source of hi h-frequency supply 18 and conventional confenser power factor correction 19.

As the sheets may be of considerable size,

and it is not desirable to distribute the induc-- tor primary over a very long length of coil, I provide for feeding of 'the composite sheet or of the coil, one with respect to the other, in

order that the inductor coil may progressively heat the sheet and fuse the coating into engagement with the metal base. "This operation normally will be carried out in the diagrammatic forms shown in Figures 2 and 3.

The edges 2O of the sheets are electrically ,connected and are at the same time mechanically joined by any means which I show its simplest form as a clamp 21 extending lengthwise of the cylinder formed.`

These figures do not show any control lof loo the radial spacing of the secondary with respect to the primary, nor do they indicate whether it be the intention to feed the secondary with respect to the primary. Evldently my invention may be applied with or without making the spacing uniform or with or without feeding in an axial direction, omitting theadditional features where their advantages are not sought.

- It is quite desirable that the radial spacin be uniform, that positive means be provide for maintaining uniformity of the spacing, as by guides, and that feeding movement between the primary andthe secondary be provided and guided.

.In Figure 4 I have shown such means 1n a guide 22 about which the secondary may be fed so as to rovide for proper spacing of the secondary rom the primary 17. *The pr1- mary is conveniently mounted upon a reduced portion 23 of the diameter of the guide and support 22. This guide is shown as hollow and is mounted upon any desirable thrust bar 24 from a support 25.

In Figure 6 the rimary 17 1s mounted within a recess 26 1n an external guide 27 whose support is shown at 28. y

Both forms of support and guide are shown in Figure 9, where two primaries are illustrated.A

In o ration the sheet of composite material is nt into curved sha and 1s mechanically held in this form at t e same time that its side or end edges, as the case may be, are

g electrically joined so as to-permit induction including that face of a secondary closest to the primary than throughout any other corresponding depth of the body of the secondary, causing higher temperature in the region vwhere the fusion ,isl desired than in the rest of the plate. Where both sides are coated or platedas would usually be the case-the entire sheet may be heated to the required temperature by either an inside or outside inductor, where the sheet is 3 thin, or the inner face of the sheet may be heated to fusing temperature by the use of an inside inductor and the outside of the sheet may be heated to the same temperature by the use of. an outside inductor where the thickness of the sheet makes this desirable.

As shown in Figure 9 inductors may be used both insideand outside the sheet during the same travel. A

Where the heating takes place wholly Vfrom one side the support or guide can be of metal since the tendency of the current to traverse the skin closest to the inductor will insure that the heatin effect will be concentrated in that face. 0 course the heat must be ap- 'plied rapidly enough to avoid undue conduction heat losses. The guide or support may very acceptably be made of a refractory.

Where the length of the bent sheet is too long for the use of a stationary coil, the bent sheet with its electrical conducting connecting strip, or strips, to insure completion of the circuit, may be moved rogressively over or wit-hin the inductor coil) ductor coil and within the other, by successive increments of movement at a speed 'ust rapid enough for pro r fusion to take place between the coating t e metal base and without excessive meltln of the metal base until the entire area of t e plate which was intended to be treated has been so treated. The tendency of the induced current to increase the coupling by traversin tion of the secondary nearest to th primary and the dlfference normally existing in the conductivities of the met-al base and the coating both contribute to a relatively excessive flow of current through the coating or covering. The fact that the coating or covering usually meltslat a much lower temperature also helps to give as good results at a lower temperature than 'would otherwise be effective. l

As a result of the fusion the sharp line of demarcation between a plating or coating or other covering andthe base metal gives way to a blending of the two metals across the initial division line, giving a resultant metal structure closely akin to that illustrated diagrammatically at 29 in Fi ure 8 in which one coating only is shown. ilar condition would exlst as to the other coating if both sides be coated.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the or over one inv that por- I e inductor simtao

ing or coating into union with a base sheet of metal normally havingfree ends which consists in folding a normally extended coated metal sheet into cylindrical form, in forming electrical connections between the ends, in inducing high-frequency'current in the exterior circumferential surface of the cylinder so formed to produce a temperature about the circumference suflicient to fuse the coating iso . both primary inductions and in straightening into Contact with the base metal and in straightening the sheet back to sheet form.

2. The met od of fusing an adherent covering or coating into union with a normally eX- tended `metal sheet which consists in coating the sheet, in bending the sheet, establishing electrical connection between the edges as bent and inducing high-frequency current How in the circumferential surface of the sheet as bent to produce a temperature about the circumference suiicient to fuse a. coating into contact Vith the base `etal and in straightening the sheet.

3. The method of fusing an adherent covering or coating upon a normally extended coated metal sheet into fused engagement `with the backing metal, which consists in bending the sheet, establishing electrical connection between the edges as bent and inducing high-frequency current flow in the sheet as bent to fuse the coating to the adjacent metal of the sheet about the circumference of the sheet, while maintaining substantially uniform spacing between the sheet and the inducing primary and in straightening the sheet back to sheet form.

4. The method of fusing an adherent covering or coating upon a normally extended metal sheet into fused union with the backing metal, which consists in bending the sheet, establishing electrical connection between the edges as bent, inducing highfrequency current flow in the sheet as bent to fuse the coating to the adjacent metal of theI sheet about the circumference of the sheet, progressively moving the bent sheet transversely to the planes in which the sheet is bent to cause travel of the induction progressively throughout the length of the bent sheet and in straightening the sheet back to sheet form.

5. The method of fusing an adherent covering or coating upon a normally extended coated metal sheet into :fused union with the backing metal., which consists in bending the sheet, establishing electrical connection between the edges as bent, inducing high-fre quency current flow in the sheet as bent, progiessively moving the bent sheet to cause travel. o the induction progressively throughout the length of the sheet, in maintaining uniform distance between the bent sheet and the iuductor primary and in straightening the sheet back to sheet form.

6. The me Lhod of fusing an adherent covering or coating upon a normally extended coated metal sheet into fused union with the backing metal. which consists in bending the sheet, establishing electrical connection between the edges as bent, in passing high-frequency primary current outside of it and also inside of it to cause it to act as secondary to tothe sheet back to sheet form.

7. 'The method of fusing an adherent covering or coating upon a normally extended coated metal sheet into fused union with the backing metal, which consists in bending the sheet, establishing electrical connection between the edges as bent, in passing high frequency primary current outside of it and also inside of it to cause it to act as secondary to both inducticns, in progressive] passing the bent sheet through the elds o both inductions and in straightening the sheet back to sheet form.

8. The method of fusing an adherent covering or coating upon a normally extended coat ed or covered metal sheet into fused union with the backing metal, which consists in bending the sheet with the covered or coated side out, in establishing electrical connection between the edges as bent, in passingJ high frequency primary current outside o? the sheet to cause it to act as a secondary to the primary and in straightening the sheet hack to sheet form.

9. The method of fusing an adherent covering or coating upon a normally extended coated or covered metal sheet into fused union with the backing metal, which consists in bending the sheet with the covered or coated side inside, in establishing electrical connection between the edges as bent, in passing high frequency primary current inside of the sheet to cause it to act as a secondary to the primary and in straightening the sheet back to sheet form.

HEINRICH NEUHAUSS. 

